The word "Church" properly speaking refers to the building and obscures the fact that the Greek word refers to the gathering of people. So people often think that Jesus is knocking on the door of their Church-house. That seems anachronistic here.
The next logical door would be to a man's home. This, I believe is a family setting. Possibly a Passover setting. A Jewish family welcomes in the messiah while the leaders of the Jewish theocracy slam the door in his face:
The criticism of the complacent could be an allusion to Matthew 25:
Mat 25:38 When saw we thee a stranger, and took thee in? or naked,
and clothed thee? Mat 25:39 Or when saw we thee sick, or in prison,
and came unto thee? Mat 25:40 And the King shall answer and say unto
them, Verily I say unto you, Inasmuch as ye have done it unto one of
the least of these my brethren, ye have done it unto me.
However, this is not about merit but about opportunity. To merely open the door is all the merit needed. The meal is celebratory.
More in the vein of Revelation 3:20 is this. In this parable a king throws a banquet for his son and invites his friends. They all can't be bothered. So instead he turns to the poor:
Mat 22:2 The kingdom of heaven is like unto a certain king, which
made a marriage for his son, Mat 22:3 And sent forth his servants to
call them that were bidden to the wedding: and they would not come.
Mat 22:4 Again, he sent forth other servants, saying, Tell them which
are bidden, Behold, I have prepared my dinner: my oxen and my fatlings
are killed, and all things are ready: come unto the marriage. Mat
22:5 But they made light of it, and went their ways, one to his farm,
another to his merchandise: Mat 22:6 And the remnant took his
servants, and entreated them spitefully, and slew them. Mat 22:7 But
when the king heard thereof, he was wroth: and he sent forth his
armies, and destroyed those murderers, and burned up their city. Mat
22:8 Then saith he to his servants, The wedding is ready, but they
which were bidden were not worthy. Mat 22:9 Go ye therefore into the
highways, and as many as ye shall find, bid to the marriage. Mat
22:10 So those servants went out into the highways, and gathered
together all as many as they found, both bad and good: and the wedding
was furnished with guests. Mat 22:11 And when the king came in to
see the guests, he saw there a man which had not on a wedding
garment: Mat 22:12 And he saith unto him, Friend, how camest thou in
hither not having a wedding garment? And he was speechless. Mat
22:13 Then said the king to the servants, Bind him hand and foot, and
take him away, and cast him into outer darkness; there shall be
weeping and gnashing of teeth. Mat 22:14 For many are called, but
few are chosen.
Jesus warns that they are in danger of being refused (vomited out). What Jesus warns could happen is what does happen:
Act_13:46 Then Paul and Barnabas waxed bold, and said, It was
necessary that the word of God should first have been spoken to you:
but seeing ye put it from you, and judge yourselves unworthy of
everlasting life, lo, we turn to the Gentiles.
The refusal by the Jewish leadership (which God accomplished by hardening their hearts) opened the way for the gentiles:
Rom 11:11 I say then, Have they stumbled that they should fall? God
forbid: but rather through their fall salvation is come unto the
Gentiles, for to provoke them to jealousy. Rom 11:12 Now if the fall
of them be the riches of the world, and the diminishing of them the
riches of the Gentiles; how much more their fulness?
IF the meal is a Passover then this is a reference to the new covenant because the Passover meal is the making an exhibition of Christ's death as the covenant victim:
Heb 9:16 For where a testament is, there must also of necessity be
the death of the testator.
Or in modern English:
A covenant requires that the covenant maker seal the deal with a
Jesus is the death God provided to ratify the new covenant with the houses of Israel and Judah.
The Passover/Seder was celebrated in individual homes, not communally like "the Eucharist". In fact, some Corinthians tried having a communal "Lord's supper" and Paul said "Don't you have houses?". See 1 Cor 11:17ff.
So to answer the original question I would say the text describes a man opening his "castle" to Jesus and them eating together. Personally I am inclined to think it was a Seder.
KJV unless otherwise noted